[Study on the relationship of thallium exposure and outcomes of births]

Objective: To investigate the relationship of thallium exposure and outcomes of births. Methods: A total of 3 236 mothers who had visited in Ma'anshan Maternal and Child Health-Care Hospital between May 2013 and September 2014 were included in this study and their thallium concentrations measured from samples of maternal and umbilical cord blood by inductively coupled plasma mass spectrometry. The results were correlated and evaluated with birth outcomes of the infants, using the multiple linear regression method. Results: The median (P(25)-P(75)) of thallium levels in first trimester, second trimester and umbilical cord blood were 61.7 (50.8-77.0), 60.3 (50.8-75.2) and 38.5 (33.6-44.1) ng/L, respectively. After adjustment for potential confounders, the thallium levels showed an inversely significant association with birth head circumference (unstandardized β coefficient=-0.41, 95%CI: -0.76- -0.06) in the first trimester blood, and associated with reduced birth length (unstandardized β coefficient=-0.65, 95%CI: -1.25- -0.05) in umbilical cord blood. However, there appeared no significantly associations with birth weight, length and head circumference (P>0.05) in second trimester. On stratification by sex, in girls but not in boys, the thallium levels were adversely associated with birth head circumference (unstandardized β coefficient=-0.53, 95%CI: -1.05--0.01) in the first trimester and were associated with decreased birth weight (unstandardized β coefficient=-277.08, 95%CI: -485.13- -69.03) and length (unstandardized β coefficient=-1.39, 95%CI: -2.26- -0.53) in umbilical cord blood thallium. Conclusions: Thallium exposure appeared a gender difference in newborn birth outcomes. In the first trimester, it was negatively associated with the birth head circumference, in the umbilical cord blood, and reduced birth weight and length in girls.